The copolymerization of tetrafluoroethylene with the comonomers specified above to make melt-fabricable, i.e., melt-processible, copolymers can be carried out in an aqueous reaction medium in the presence of a dispersing agent and an initiator. A commonly employed dispersing agent for this polymerization is ammonium perfluorooctanoate, C.sub.7 F.sub.15 COONH.sub.4. Use of other dispersing agents with superior performance has long been a goal.